Tugai forests at the Tarim middle reaches, Xinjiang, China ecology, conservation, and restoration Niels Thevs Institute of Botany and Landscape Ecology Greifswald University -

Contents 内容 Introduction into the term Tugai 介绍图加以森林的概念 Introduction of the study area, the Tarim Huyanglin Nature Reserve (geomorphology, hydrology, people and land use) 介绍塔里木胡杨林自然保护区，包括地貌、水文、人与土地利用 Introduction of the two research items spatial distribution of Tugai vegetation and recruitment of Tugai forests with methods and results 介绍Tugai植被分布与胡杨林繁殖的研究工作 Conclusions regarding conservation of the Tugai vegetation 保护胡杨林方面的结论 Cooperation of the Institute of Resource and Environmental Sciences of Xinjiang University and the Institute of Landscape Ecology and Botany of Greifswald University

Definition of the term Tugai forest 介绍土加以森林的概念 Riparian forests of the deserts and semi-deserts of Central Asia. 中亚沙漠的河岸林。 Tugai forests are mainly built by Populus euphratica, Populus pruinosa, Elaeagnus oxycarpa, and Salix species. Populus euphratica、 Populus pruinosa、 Elaeagnus oxycarpa、Salix的几个种就是建土加以森林的树木。

Ecological functions of Tugai forest 土加以森林的生态作用 Tugai forests are the hotspot of biodiversity in the deserts of Central Asia. 土家以森林在中亚沙漠集中生物多样性。 They serve as windbreak, serve for sand fixation and provide fodder and shelter for wild and domestic animals. 生态作用是治风速、固定风沙、给野生动物与畜牧提供饲料与保护。

Destruction of Tugai forests 土加以森林的破坏 Xinjiang, China: 1958: 500,000 ha Tugai forest 1978: 150,000 – 350,000 ha Aral Sea Basin / Amu Darya: 1950: 500,000 ha Tugai forest 1998: 70,000 ha

Strategy to survive in the desert environment 在沙漠环境生存的战略 P. euphratica, as well as the other species of the Tugai forests, is a phreatophyte. 胡杨是所谓的。 Phreatophytes continuously contact the groundwater and thus ensure their water supply. 它不断的连通与地下水，使保证它的水提供。 P. euphratica can live on groundwater as deep as 12 m below surface. It forms the Tugai forests along the Tarim River. 胡杨可以生存以12米深的地下水位。 The groundwater mostly is replenished by river courses. 地下水是由河流提供的。

Recruitment of Populus euphratica 胡杨的繁殖 Seeds germinate after floods on moist, non-saline, freshly deposited river banks free of other vegetation. Seeds germinate in belts according to flood lines. 胡杨种子洪水后在又湿润、盐分不高、新沉下来的，又没有其他植被的河岸发芽。种子沿着洪水位的线发芽出来。 On non-flooded sites P. euphratica trees reproduce vegetatively. Older stands are composed from clones. 没有洪水地点上胡杨通过根系统发芽出来。因此老胡杨林子由几个克隆成分的。

Research objectives 研究对象 Investigate the current distribution of Tugai forests and other Tugai vegetation. 研究目前土加以森林和土加以植被的分布。 Investigate the conditions needed for the recruitment Populus euphratica as key-stone species of the Tugai forests along the Tarim River. 研究胡杨繁殖对生态条件的要求。 Conclusions for conservation of the Tugai forests and Tugai vegetation. 土加以森林和土加以植被保护的结论。

The study area (Tarim Huyanglin Nature Reserve) 研究区域（塔里木胡杨林自然保护区）

Monthly discharge of the Tarim at Yingbaza 塔里木河英巴扎月流量 The Tarim River is fed by precipitation (summer maximum) in the mountains (mainly Tianshan) and melting water. 塔里木水来源就是天山融水、降水。 Each flood can alter the river course, as the Tarim River flows in a level flood plain. 每次洪水改河道。 Data provided from Tarim Watershed authority and Prof. Nurbay Abdusalih

River course changes of the Tarim Source: Hedin (1905) 1949 (light grey: Tarim 1903) Source: China Geodesy Bureau (1959) 1973 (light grey: Tarim 1949) Source: Landsat MSS 1973/10/20 2000 (light grey: Tarim 1973) Source: Landsat ETM 2000/07/06 Boundary of the Tarim Huyanglin Nature Reserve

Tamarix dunes, P. euphratica stands on fluvial sediments

P. euphratica stand at the desert margin

Tugai forest, periodical river branch of the Tarim River

Flood marks from 2006-summer-flood

Tarim River at Iminqäk

Regulation of the Tarim River 塔里木河的治理 Objective: Ensure water supply for the lower reaches of the Tarim after 30 years of drought. 目标： 塔里木下游干30年了后保证下游的水提供。 Tarim Watershed Administration, 2003 Measures 措施: Divert water from the neighboring Kaidu-Kenqi watershed into the Tarim lower reaches. 由开都-孔雀河流送水往塔里木河下游。 Construct dykes along the main river course of the Tarim to channel water through the inland delta down to the lower reaches. River branches are cut off. 沿着塔里木河干流建堤坝，把水通过中游的内陆三角洲送到下游。塔里木内陆三角洲的支流被打断了。

Poeple and land use 当地人民与土地利用 Traditionally Uyghur people herd sheep and goats and have small fields and gardens around villages. 传统维族人放绵羊、山羊，乡村周围种地。 After 1995 large scale cotton fields were opened, mostly by Han-Chinese from outside the area. 1995年以来大面积开耕，种棉花，大部分的承包土地人是外地人。 After 2003 „ecological“ resettlements were conducted (e.g. Caohu). After local people had been settled away, the land was given to new immigrants and the area under cotton was enlarged. 2003年以来进行“生态移民”。如草湖乡，当地人以民走了后，外地老板承包草湖乡的耕地，而扩大耕地面积。

Investigation of the current distribution of Tugai forests and other Tugai vegetation methods 研究目前土加以森林和土加以植被的分布 — 方法 Classification of two Landsat ETM images to derive a land cover map. 分析两张Landsat卫星片，造土地覆盖图。 Images: path 144, row 31, 2000/07/06 (representing base flow), 2001/08/10 (representing flood). 卫星片: path 144, row 31, 2000/07/06 (洪水前), 2001/08/10 (洪水季节). Ground truth data: 286 vegetation samples, 145 training sites, 141 validation sites. 地表数字：286植被样地。

Recruiment conditions methods 研究胡杨繁殖对生态条件的要求 — 方法 Investigation of Tugai forests formation (vegetation map, tree ages, soil sampling) at a still natural site with river relocation (site in Iminqäk). 通过植被图、年轮、土壤分析，在自然的胡杨林（移民且克）研究土加以森林形成过程。

Transect Ia Iminqäk – river course changes 移民且克样带 — 河流改道 transect Iminqäk

River bank changes at transect Iminqäk 移民且克样带河岸迁变 Background: Quickbird image, 2005/06/15

Transect Iminqäk - elevation, soils, vegetation 移民且克样带 — 高度剖面、土壤、植被 Tarim river bank between 1973 and 1992 1973年和1992年之间的河岸 P. euphratica row from germination before 1992. 胡杨线，1992年前发芽的。 P. euphratica shrubs in between: root suckers. 胡杨线之间的灌木由根发芽的。 Germination belt from 2002 2002年的种子发芽胡杨带

Discussion I 讨论 I Dense Tugai forests are restricted to belts of 1 km width along river courses. Tugai shrubs occur still further away from river courses. 比较密的胡杨林（土加以森林）分布在河流左右边1公里宽的带。土加以灌木（红柳) 1公里的带以外可生存。 The large contiguous area of Tugai forests in Iminqäk is a result of a dense web of river branches, which are still flooded. 移民且克大面积很宽的土加以森林就是支流很密的三角洲的效果。

Discussion II 讨论 II Germination frequently takes places, but establishment is the bottleneck. 胡杨种子经常发芽，但很少长大树。 Seeds germinate in autumn and seedlings have to survive the spring and summer of the following year. During spring and summer the groundwater level drops 2,5 – 3 m below surface at the germination site. 种子秋天发芽，幼苗必须经过第二年洪水前的春、夏天。春、夏天地下水位降到2.5-3米。 Seedlings may survive either through an early onset of the flood in the year after germination, or seedlings may survive through silty and clayey soil layers, which store water better than sand. 幼苗通过早的洪水或保持水分的粘土层可继续活，长连通地下水的根，长成大树。

Conclusions regarding conservation and restoration of Tugai forests 保护与恢复胡杨林方面的结论 River courses without dynamics replenish the groundwater and thus sustain existing Tugai vegetation. 没有河流改道的河流可保持一定的地下水位，而保持已经存在的胡杨林。

River courses with dynamics and flood events foster the generative reproduction and establishment of P. euphratica as key-stone speices of the Tugai forests along the Tarim River and maintain the genetic diversity of this species. 洪水和河流改道使胡杨种子发芽而幼苗长大的过程，保持胡杨的基因多样性。 River dynamics and flood events are the key-factors for the conservation and restoration of Tugai forests. 洪水和河流改道就是保护胡杨林的核心因素。 River course stretches with still prevailing river dynamics, i.e. Iminqäk, should become core zones for the conservation of Tugai forests. 保持河流改道的河段（如移民且克）应该作为保护胡杨林的核心区。

Conservation and land use 保护与土地利用 Animal herds must be kept away from P. euphratica seedlings. Herd sizes must be limited within the Chengbao-Contracts on land tenure. Herding with limited herd sizes can leave space for nature, as we found in Iminqäk. 应该避免有幼苗的地方放牧。承里应该限制畜牧数量。 Irrigation agriculture (i.e. cotton) must be taken out of the Tarim Huyanglin Nature Reserve. Growing reed might be an alternative. 在自然保护区应该停止种棉花。可能可利用芦苇以经济来源。 Ecological resettlement must be stopped, because the local people know better to deal with the Tugai vegetation than the immigrating people. „生态移民“应该停止，因为当地人适应当地自然比外来人好。

Abandaned cotton field, Iminqäk

Thanks to the colleagues and funding organisations: The colleagues from Xinjiang University and Bügür: Prof. Nurbay Abdusalih, Muzappar Mijit, Dr. Ümüt Halik, Prof. Mijit Hudaberdi, Prof. Huang Peiyou, Li Daping, Ghalip Jan The supervisors and colleagues from Greifswald University: Prof. Succow, Prof. Zerbe, Prof. Schnittler Jan Peper, Philipp Pratap Thapa, Franziska Gahlert, Susanne Abel, Nadine Jeschke, Martin Wiehle Funding organisations: Volkswagen Foundation, Heinrich-Böll-Foundation, DAAD